DougCoMo said:
The point I'm trying to reach is if the helper in the suit doesn't move at all or only perhaps 18 inches upon impact, how much impact occurs numerically (the increase in lbs energy?). The dogs can break canines, have disc injuries etc. We're trying to relate that the weight at speed needs to be well absorbed through movement (less direct impact) and then returning the dog quickly back to the ground. I had someone tell me it's like being impacted by 566 pounds and I have no idea if this even close.
It seems to me that a direct impact between the centers of mass of running-jumping dog and static suspect seldom occur.
By watching these slow motion videos, we can see that the dog goes for one of the arms of the subject, which makes it use some of its impulse to jump in order to bite higher.
Then, a natural rotation of the suspect's body happens, which dramatically reduces the efect of the impact on the balance of the subject.
The fun part starts when the impulse of the dog takes it to the opposite side of the original trajectory and pulls the entire body of the suspect via its canines bitting his arm.
I believe that it is at that point when the dogs can break canines and have disc injuries, because the material of the protecting gear does not tear and yield as flesh and skin do.
The training subject does not feel pain either, therefore he does not go along with the impulse of the body of the dog, like a real suspect would do naturally trying to minimize pain and flesh damage.
In nature, the canines are strong if they can penetrate skin and flesh of an animal, because as the wolf shakes his head and body to tear flesh and to increase pain and bleeding, the associate huge forces are uniformly distribuited closer to the root of the canines.
Bitting on the surface of the protective gear makes the canines of a police dog more vulnerable because the forces that could break them are applied to the tip rather than the section closer to the gum (greater moment or torque applied at the root).
Same for the spine discs, if the spine is no aligned when traction or compression or twisting forces happen.
Perhaps adding some elasticity or yielding capability to the usual areas of bites in the garmet could aliviate dog's injuries, as well as training on more yielding movements to "pain" from the helpers.
All the above makes any calculation complicated.
A way to experiment about the effect of pure impact could be launching a bag of sand against the body of a standing man.
That man could try catching that bag off center and try holding it while it rotates to the opposite side.
Of course, that would leave the pain effect out of the situation.